Best Nano reef tanks: 6 Small Fish Tank Reviews and Ratings

Nano reef tanks have become increasingly popular and have generated a lot of interest from beginners and experienced fish enthusiasts alike.

The maximum number of gallons that can be called a nano aquarium has been a debatable point, with some saying 20 gallons, or 30, ranging all the way up to 40 gallons.

In this article, the largest tank we review is 15 gallons, though most are around 5 gallons. These are more like pico tanks.n

Regardless of the exact size, they are smaller than most other aquariums, which means that people are able to keep fish in places they were not able to before.

Best Nano reef Tanks Quick-Find Table

Benefits of a nano aquarium

1. Size – put it anywhere!

The most obvious benefit to having a nano reef tanks is the smaller size.

With some as small as 2.6 gallons, fish tanks aren’t just for the living room anymore.

Now, spaces such as office cubicles, desktops, and dorm rooms are able to support your fish habit.

Because of the fewer number of gallons of water they are able to hold, they are also lighter than traditional tanks.

Author Note: Gone are the days when you need a reinforced floor and a huge stand to own a couple of fish. Now they can fit comfortably on that table or desk you have in the corner.

2. less Maintenance

Because of the smaller size, nano aquariums are easier to take care of.

There is less surface to clean and less water to change, meaning you have more time to enjoy your pets.

Top Tip: Keep in mind that you still need to do all of the usual maintenance, it’s just on a much smaller scale.

3. Lower prices

Another selling point to many is the price.

Logically, if a tank is smaller than another tank, it will be cheaper to manufacture, and is therefore cheaper to the public.

Maybe you’re just getting started, or maybe you just want something so your kid stops bugging you about getting a pet. You may not want to spend the hundreds of dollars to get a large system set up.

These micro tanks offer a fantastic solution, allowing you to get your feet wet (hopefully not literally!) without shelling out the big bucks.

Limitations of a nano Reef tanks

However, everything has drawbacks, and nano reef tanks are no exception.

Because of the smaller amount of water and space, there is less room for error.

A high amount of nitrates can be bad for fish in a large tank, but you may have time to correct it before it becomes hazardous.

Author Note: In nano reef tanks, you don’t have the luxury of time, and a problem like that can be deadly for your fish in a matter of days, or even hours if the problem is something like a malfunctioning air filter.

Having a smaller tank also cuts down on the number and size of the fish you are able to keep.

More than likely, you will not be able to house anything that grows to more than three inches, and you would be limited on the number.

So if you are wanting a large variety or a large number of fish, or even ones that grow a little larger, than a nano aquarium might not be for you.

How we rated the nano reef tanks

There are certain things to look for when choosing the right nano reef tanks.

While they all perform the same basic function, there are differences, and getting the one that is not right for your situation could end up being more work for you…or even harmful to your fish.

Overall value is what most people look at when making purchases.

Most of these tanks come with the necessary equipment, but some require additional purchases, such as heaters, extra lights, or even lids, to complete the set up.

You need to look at what your specific needs are and what tank best fits those needs.

Quality is an important factor and can play a big part in whether your nano tank thrives or not.

You don’t want to have to replace equipment every few months, or even the tank itself. There is no need to buy the aquarium that costs less if you’re going to have to replace it because it starts leaking.

Maintenance needs were another factor taken into account when choosing the best nano aquariums.

Despite their similar structures and functions, some tanks require more upkeep than their counterparts.

Top Tip: If you are new to keeping fish, or simply do not have the means or desire to spend a lot of time on maintenance, this needs to be taken into account when choosing your new aquarium.

Learn More: 23 Best Fish for Stocking 5-Gallon Aquariums

Reviews of the best nano reef tanks

There are a lot of tanks to choose from on the market today, but these first two are the best out there.

Author Note: Quality craftsmanship, great features, and competitive prices mean that these nano aquariums will be the perfect fit for both you and your fish.

Fluval makes a quality product, so if cared for properly, this tank should last you and your aquatic friends a long time.

The filtration system is excellent and should have no problem keeping the aquarium clean.

Note that modifications will have to be made to the filter if the aquarium is for a Betta, as the filter current is too strong. We recommend placing a sponge in the output nozzle to reduce the flow.

The lights provided in the kit are strong enough to support live plant growth, which is an important feature for those looking for a more natural environment for their fish.

This saves you the expense and hassle of having to buy new lights and figure out how to mount them in the tank.

The filter and pump are both very quiet, so there is minimum disruption to both you and your living or work space.

They are placed in a compartment that is not visible when viewing your fish, and all of the wires come out from the same place. This makes for a very neat and tidy look, so making this the focal point of a room is absolutely an option. 

Last, but certainly not least, the kit does come with instructions that are easy to read and in several different languages. This makes setting up this tank pretty easy, even if you have never done it before.

This Youtube video from Alyssa Nicole shows her first time setting up this tank.

Product specifications

• Size: 5 gallons
• Dimensions: 17 in. L x 6.5 in W x 10.5 in. H
• Comes with: three stage filtration system (which includes a filtration sponge, carbon filter bag, and a biomax filter bag), LED lights, an adjustable flow circulation pump, outlet tube and nozzle, and the lid.

Things we loved

1. The tank is made of etched glass, which is extremely attractive
2. The lights are bright enough to support live plants
3. The pump motor runs quietly
4. The honeycomb patterned mesh conceals the pump and filter
5. When problems arose with products or the tanks themselves, Fluval customer support took care of problems right away and were very courteous

Things We Didn’t Love

1. A filter sponge or similar modification will need to be made if a Betta is being housed in this tank as the filter current is too strong
2. The rear compartment that houses the pump and filter is small and can be hard to clean for some

While not the cheapest nano aquarium on the market, it is not the most expensive either.

And for those who believe that you get what you pay for, this tank is a terrific value.

While modifications have to be made to the filter, that is a standard problem for any of the 5 gallon or smaller tanks.

But the quality of the products included, as well as the quality of the tank itself makes this the top choice for me when purchasing my next nano aquarium.

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The three stage filtration of the Marineland Contour means the filter is extremely effective at keeping your tank clean and ensuring your fish stay healthy (super important for small tanks!).

Despite this, it is extremely quiet, as is the pump, so there is little disruption for either you or your fish.

As with many of these tanks, the filter current is a bit strong for Bettas and shrimp, so modifications like a sponge in the outflow nozzle should solve that issue.

The pump and filter are also hidden from view, so your small tank doesn’t look cluttered. This back compartment is small, so a scrubber will probably have to be purchased to clean it, since a hand will likely not fit all the way to the bottom.

The lights included in this kit are enough to be able to grow low level plants. If you want plants that require a higher level of light, then new lights will have to be purchased separately.

However, the lights are connected to a rail that sits above the tank, so it will be very easy to modify your lighting system if and when you decide to.

Product specifications

• Size: 3 or 5 gallons
• Dimensions: 9.5 in. L x 9.5 in. W x 9.5 in. H (3 gallon) and 9.5 in. L x 9.5 in. L x 14 in. H (5 gallon)
• Comes with: three stage filtration system, utilizing chemical, mechanical and biological filtration, LED lights with daylight and moonlight settings, a base

things we loved

1. The pump doesn’t make much noise
2. The glass canopy slides back for easy access to the inside of the tank
3. The curved glass design makes it very sleek and attractive
4. The filtrations system is very efficient
5. The lights support live plants

Things we didn’t love

1. The cover for the rear compartment is a little flimsy
2. The rear compartment housing the filter and pump is a little cramped and hard to clean

Marineland has been around for decades and is known for producing high quality products. This tank would make a great addition to your home or office and is one of the best products for your money.

Having said that, I would choose the five gallon tank over the three gallon.

The five gallon is a little more expensive, but your fish would certainly appreciate the extra swimming space, and the footprint of the five gallon is not much more than the three gallon.

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While these next four did not make the Top 2 list, they are still high quality nano aquariums that would be a great home for your fish.

The Tetra Cube utilizes a Tetra 3i filter, which does an admirable job of keeping the nano reef tanks clean. However, it is also a little too strong for a Betta. 

The current may push it around, and severely limit where your fish can swim in the tank. It’s also fairly loud, and some people replace it for that fact alone.

The LED lights that come with this kit do not have adjustable settings like so many of the other tanks on this list.

If your Betta is sensitive to light, for example, you will have to alter the light placement somehow or just buy a new kit, as the brightness can put stress on the fish. You can also place some floating plants on top to give him somewhere to hide.

This small aquarium is made out of plastic, which some people seem to love and some seem to hate.

It scratches easier than glass, but you can see the fish just as well as you can in a glass tank…until it’s totally scratched. But really, how many times is something going to get close enough to scratch it? Not a huge concern.

Product Specifications

• Size: 3 gallons
• Dimensions: 9.5 in. W x 9.5 in L x 10 in. H
• Comes with: LED light, filter, air pump, base

Things we loved

1. The raised base is very solid
2. The lights can support low level plants
3. Has a sleek and simple design
4. Can fit just about anywhere

Things we didn’t love

1. You may choose to replace the filter for something quieter/more durable
2. The pump is loud, so you may want to replace it with a different model
3. The acrylic the tank is made of scratches easily

Knowing I would have to replace both the filter and the lights, I would spend my money on one of the other tanks on this list.

If I happened to have these parts laying around from an old tank, then it’s a good tank for the money.

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One of the first things people notice about the Marineland Portrait is the curved edges. This gives the tank a very elegant and sophisticated look, making the tank look more expensive than it is.

Besides looking great, and making it easier to clean, this also allows you views of the tank and your fish that you cannot get with rectangular corners.

The three stage filtration system includes carbon in the filter, which takes care of chemical filtration, while the biofoam performs the biological and mechanical stages of filtration.

This system and the pump, as well as a heater if you are going to add one, are hidden in the back, and run very quietly, so they do not detract from the beauty of the tank or distract you while watching your fish.

The lights included in this tank are LED, and meant to mimic sunlight and moonlight. There are nine white and six blue lights that hover over the tank from a plastic stand.

These nano reef tanks are bright enough to support live plants, but only those that require low level light. For brighter lights that can support higher level plants, a new light kit will have to be purchased.

The Portrait is a little taller than most of these nano aquariums. This gives you a little more room when decorating, as the tank can accommodate taller decorations.

If you have Bettas, they will appreciate this, as they often like swimming close to the surface and the taller décor may give them something to rest on.

The Portrait does come with an instruction manual, and there are plenty of videos on Youtube showing how easy the setup for this tank is.

Product specifications

• Size: 5 gallons
• Dimensions: 9.63 in. L x 9.63 in. W x 14 in H (17.2 with the base)
• Comes with: Three stage filtration system, white and blue LED lights, an adjustable flow circulation pump, a sliding canopy, and a base

Things We Loved

1. Lights can support low level plants
2. Filtration system is very efficient
3. The motor for the pump is quiet
4. The canopy holding the lights flips up for very easy access
5. Curved edges make it a very attractive piece

Things We Didn’t Love

1. Filtration system needs to be modified for Bettas
2. The cover over the rear compartment is flimsy
3. Some people find that the lid doesn’t fit correctly when a heater is added

Since Marineland is known for putting out a quality product, it’s hard to go wrong with this tank.

It is a little taller than most of these tanks, especially when you factor in the base, so that needs to be taken into account if that will be an issue for you. 

The only noticeable differences between this tank and the Marineland Contour are the differences in height and the provided light kit.

So it really comes down to personal preference. Either one is a great value. This video from Hicksterpets on Youtube does a good job of contrasting the two.

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The filtration system and the pump both run pretty quietly, but still manage to perform efficiently, which is important for a small tank like this.

The current has been said to be a little strong for some Bettas, but the filter has a knob to adjust the flow. You should be able to keep your fish happy by simply lowering the current level.

You may need to watch out for quality issues, which is why this isn’t higher on the list, as sometimes the hinges on the lid are missing, broken, or installed incorrectly.

This becomes inconvenient when one of the selling points of the tank is the lid that makes it easy to feed your fish and clean the tank.

The point of nano aquariums is to offer a smaller tank with a smaller footprint, but it is said often that even Bettas, who are known for living in very small containers in pet stores should have a minimum of three gallons.

These nano reef tanks come close, and it’s clear from the many people who love this that most bettas will do well here.

Product specifications

• Size: 2.7 gallons
• Dimensions: 9 in. L x 8 in. W x 10 in H
• Comes with: Attachable water filter, digital water temperature thermometer, fish net, lid

Things We Loved

1. Great tank for beginners
2. Has a hinged lid that makes it easy to open for feeding and cleaning
3. Pump is pretty quiet

Things We Didn’t Love

1. No lights are included
2. Filtration system needs either needs to be modified or turned way down for Bettas
3. The small size means it’s really only adequate for a Betta or shrimp

If I was getting a tank for myself, I would have to pass on this one and go with one of the bigger models that included a light kit.

But if I were getting something for my kids to put in their rooms, this one would be near the top of the list.

Especially if you have very small fish or shrimp this is great for beginners and is a nice introduction into the world of owning fish.

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Like the other Fluval products, the Flex comes with the three stage filtration system that includes the foam for mechanical filtration, the activated carbon for the chemical filtration, and the Biomax for the biological filtration.

Again, the current is a little strong for a Betta and similar fish, but that can be easily rectified with a sponge into the outflow nozzle.

The pump and filter are hidden in a rear compartment, so they do not detract from the view of the tank and your fish.

The lights for this tank are the most elaborate on this list by far.

There are red, blue, green and white LED lights. There are also certain special effects like lightning bolts and cloud cover to stimulate your fish. They are bright enough to support live plant growth without having to make any modifications.

Because of its size, this tank offers a lot more than any other tank on this list in terms of options for fish, décor and plants.

If you want a smaller aquarium that doesn’t take up half your wall, but still want to be able to house more than one fish, than this tank is a great choice. It’s a Fluval, so you can be confident that you are getting a great value.

Product specifications

• Size: 15 gallons
• Dimensions: 16 in. W x 15 in. L x 15 in H
• Comes with: Three stage filtration system, LED lamp with remote control, circulation pump

Things We Loved

1. The lights support live plants
2. The lights have red, green, blue and white colors, along with special effects like lightning bolts
3. The pump is quiet
4. High quality

Things We Didn’t Love

1. The curved glass may distort the view of the fish
2. It is not easy to modify the lights if you want to change out the ones it comes with
3. The rear compartment housing the filter and pump is large, which brings the actual living space to about ten gallons

This tank is manufactured by Fluval, so the quality is certainly up there with any of the tanks on this list.

Because this nano aquarium is a little bigger than any other one on this list, there are certainly a lot more options in terms of number and variety of fish, number of plants and the number and types of decorations.

Personally, I tend to either favor the really small tanks or the bigger ones.

I like my little micro tanks set up on the kitchen counter and am saving up for a 125 gallon one for the living room.

But if you like the mid size tanks, then the Flex would be a perfect fit for you.

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Nano Reef Tanks FAQs

If you’ve got questions about nano tanks and what exactly they are and how they work, these FAQs should help.

What is a Nano Reef?

A nano reef is what is sounds like – a nano (tiny) coral reef created at home in a small fish tank.

Typically they contain sand, live rock, corals, and other aquatic life.

Many folks keep fish, shrimp, anemones, and other invertebrates that natively thrive in a coral reef at sea.

Nano reef tanks are typically only 40 gallons or smaller.

What is a Pico Tank?

Pico tanks are primarily what we’ve been looking at today: nano reef tanks smaller than 10 gallons.

Typically, pico tanks are 5 gallons or smaller.

These aquariums are not recommended for beginner aquarists, as they are extremely sensitive.

Slight water quality changes can affect the lives of the inhabitants of a pico tank dangerously, since the minor changes impact the tiny ecosystem.

Are Corals a Type of Living Rocks or Plants or Something Else?

Corals are not plants nor are they a “living rock.”

Corals are, instead, a sessile, which means they are tiny animal that attaches permanently to the ocean floor.

They “take root” like plants do – and they don’t look like what we typically think of as animals.

Each coral is made up of hundreds of thousands of polyps. They secrete a hard outer skeleton of limestone to protect themselves. This is what allows them to attach to rocks and other materials.

What Does FOWLR stand for?

FOWLR stands for “fish only with live rock.” Basically, the term refers to saltwater tanks that don’t contain corals.